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netmaster June 14, 2013 19:32

forces on particles
 
Hello all,
I was wondering if any one had a clue on how to approach a simulation model I am working on. I use Lagrangian particle tracking to introduce solid particles at the inlet of a pipe flow. The trajectories of the particles are calculated in accordance to the forces acting on it (namely just the drag force) due to the fluid flow (water). However, there are additional forces which acts on this particle such a force due to rotation of particle (called magnus force).

Is it possible to model of rotation/spinning of the particles as they travel with the flow. I anticipate that this would require the calculation of the torque on the particle surface due to fluid motion which would then give rise to the magnus force on the particle. Or is there any other way to implement it.

Any help on the topic will be highly appreciated and I thank you in advance for it.

Thanks
Aashish

siara817 June 26, 2013 09:47

Yes, it is possible to model it. When you want to model the rotation, I assume that your particles are not spherical. when you are selecting the particle phase, it is enough to select non-spherical and Composite Particles Model. It is better to read more in tutorial about Composite Particles Model.

netmaster June 29, 2013 20:12

Quote:

Originally Posted by siara817 (Post 436108)
Yes, it is possible to model it. When you want to model the rotation, I assume that your particles are not spherical. when you are selecting the particle phase, it is enough to select non-spherical and Composite Particles Model. It is better to read more in tutorial about Composite Particles Model.

Thanks for the swift reply. I want to model rotation of particles (these can be spherical also). Currently I use Lagrangian particle tracking to calculate the particle trajectories in flow. The lagrangian particle tracking calculated the drag force on the particles (viscous drag due to the slip velocity between particle and fluid), pressure gradient force and the virtual mass force. However, I want the other forces such as the near wall Saffman force and force on the particle due to its rotation in the flow field.

Are you referring to the lagrangian particle model or something else. I was not able to find the any tutorial or reference of composite particles in the user manual. Thanks again.

siara817 July 1, 2013 04:16

In your case, I do not think the Saffman force is important. Anyway, when you say you want to have a non-spherical particle in your simulation, then you need to make a particle with combination of spherical particles. from tutorial '' The DEM Particles model is represented in the Lagrangian phase by the DEM Particles node.DEM Lagrangian phases include phase models that allow you to define the shape of the particles as:Composite particles—Non-spherical particles with fixed bonds between the particle components.
Particle clumps—Non-spherical particles with breakable bonds between the particle components.
Spherical Particles—Single spherical particles.''

socreate October 15, 2014 11:27

How to calculate the pressure gradient force
 
How to calculate the pressure gradient force of the particle? Fluent is used to solve the fluid flow. C_P_G may be not a good choice to calculate the pressure gradient force, which may cause instability. So, I don't know how to do. Could you give some suggestions?

Appreciate for your help!

Best regards,
socreate


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